Nano Hybrids and Composites Vol. 25

Abstract: In this study, the Pb(II) ions adsorption unto nanoscale zerovalent iron particles (nZVI) supported on rice husk has been carried out. The challenge of nanoparticles agglomeration makes immobilising them on rice husk desirable. Optimization of process parameters, pH (4 – 10), adsorbent dose (0.5 – 2.0 g) and contact time (60 – 300 min), was carried out using response surface methodology (RSM) based on Box-Behnken design. Optimum condition for maximum Pb(II) ions of 98.74% was predicted at contact time of 60.12 min, pH of 4.01 and adsorbent dose of 0.5 g. At these optimized conditions, 97.23% removal was achieved experimentally. Analysis of variance carried out on the experimental data showed that the model was significant with a R² of 0.9883. The synthesised adsorbent was characterized with Fourier transform-infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The SEM showed that RH-nZVI has a very porous surface structure. Amine, carboxyl and hydroxyl groups were some of the identified functional groups present in the adsorbent for adsorption. This study suggests that nZVI supported on rice husk is a viable low-cost adsorbent for removing Pb(II) ions from wastewater.

Abstract: This work presents improvement of H₂S gas sensing capability by introducing TiO₂ in conductive polymer namely “MEH-PPV”. Firstly, the organic conjugated polymer poly ( 2-methoxy-5- ( 2'-ethythexyloxy) - 1,4-phenlenevinylene) and TiO₂ was dissolved in chloroform solvent. The two solutions “MEH-PPV” and TiO₂ were mixed in a volume ratio of (0.002 and 0.008) respectively and spin-coated on Si substrate for realizing facile and low-cost sensors. The X-Ray diffraction spectrum of (MEH-PPV/TiO₂) nanocomposite thin films was studied, all the pattern showed that the structure is amorphous. The morphology was demonstrated by Field Emission Scanning Electron Microscope (FESEM) images for MEH-PPV and MEH-PPV/TiO₂ films which shows formed anano flower like structure with introduces of TiO₂All films were examined by Atomic Force Microscope (AFM) which revealed the average roughness increment from 0.204 to 1.25 nm with increase the mixed rate of TiO₂. The “MEH-PPV/TiO₂” based sensors also shown noticeable responses when the sensors exposure to H₂S gas at the concentration of 25ppm. The maximum sensitivity for MEH-PPV/(0.008) TiO₂ was 528.1 at operating temperature at 100^°C, whereas the response and recovery time was ~ 21.5 s and ~3.8 s, respectively.

Abstract: Jute fabrics reinforced Unsaturated Polyester Resin (UPR)-based composites were prepared by conventional hand lay-up technique. Different proportions (5 to 50% by weight) of fibre content was used in preparation of the composite. Tensile Strength (TS), Tensile Modulus (TM), Bending Modulus (BM), Bending Strength (BS), Impact Strength (IS) of the fabricated composites were studied. Upon each addition of fiber content in the matrix, mechanical properties of the composites were increased. The Tensile Strength (TS) of the 5% and 50% fiber reinforced composites was 18 MPa and 42 MPa respectively. Scanning Electron Microscopy (SEM) showed interfacial properties of the composites and it was revealed that the bond between fiber and matrix was excellent.

Abstract: This study reports the biosynthesis of narrow range diameter silver nanoparticles at optimum conditions using Eucalyptus corymbia as a reducing and stabilizing agent. Optimal conditions for biosynthesis of silver nanoparticles (AgNPs) were found to be; an extraction temperature of 90°C, pH of 5.7 a Silver Nitrate concentration of 1mM and AgNO₃ to plant extract ratio of 4:1. UV-Visible spectroscopy monitored the formation of colloidal AgNPs. The UV-Visible spectrum showed a peak around 425 nm corresponding to the Plasmon absorbance of the AgNPs. The size and shape characterization of the AgNPs was done using Transmission Electron Microscopy (TEM) techniques which revealed narrow range diameter (18-20 nm), almost monodispersed AgNPs, spherical in nature and with minimal agglomeration. Energy Dispersive X-ray (EDX) results showed the presence of two peaks at 3.0 and 3.15 keV in the silver region. The Fourier Transform Infrared-Spectra (FTIR) of the plant extract and the AgNPs gave rise to vibrational peaks at 3260 and 1634 wavenumbers which are due to the presence of OH and –C=C-functional groups respectively.

Abstract: Mixing of nano-sized powders with soils (macro-sized powders) is a noteworthy issue for geotechnical projects. Thus, this study examined the horizontal ball mill mixing of nano-copper oxide with kaolinite. Ball milling parameters (rotation speed, weight ratio of balls to powder and milling time) of the planetary ball milling were optimized for proper mixing of nano-copper oxide and kaolinite powder. Results showed that increase in mixing time decreased the agglomeration of nano-copper powders and kaolinite and increased the homogeneity of nano-copper powder with kaolinite particles. The quality of mixing was assessed through intensity and scale of segregation using concentration data obtained through energy dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD) analyses. It was observed through these two tests that, increase in ball milling time after 6 hours resulted in grain size reduction. Field emission scanning electron microscopy analysis showed that nano-coppers were regularly found on the surface of kaolinite particles after 6 hrs. of horizontal milling at 4:1 ratio of balls to powder mixture. Furthermore, 24 hrs. mixing resulted in grinding of kaolinite particles and hence their size was reduced. Particle size analysis confirmed these results, as the highest size span value of 3.417 was observed after 6 hrs. milling with speed of 200 rpm.

Abstract: This article presents the free vibration analysis of simply supported plate FG porous using a high order shear deformation theory. In is work the material properties of the porous plate FG vary across the thickness. The proposed theory contains four unknowns unlike the other theories which contain five unknowns. This theory has a parabolic shear deformation distribution across the thickness. So it is useless to use the shear correction factors. The Hamilton's principle will be used herein to determine the equations of motion. Since, the plate are simply supported the Navier procedure will be retained. To show the precision of this model, several comparisons have been made between the present results and those of existing theories in the literature for non-porous plates. Effects of the exponent graded and porosity factors are investigated.

Abstract: This work presents the synthesis of zinc oxide /silver sulfide (ZnO/Ag₂S) core/shell type composite; using combined wet chemical precipitation method and ion exchange mechanism; for wide range absorption of visible spectra by the composite. Synthesis is performed in three steps. In the first step; ZnO nanoparticles (nanocores) are produced, in the second step; ZnS layer is deposited over ZnO nanocores and in the third step; Zn from ZnS is replaced by Ag to form Ag₂S shell over ZnO; using ion exchange mechanism. The presence of reflection peaks of ZnO and Ag₂S in XRD spectra confirms the formation of ZnO/Ag₂S composite. SEM image of ZnO shows the formation of near spherical ZnO nanoparticles of diameter in range 256nm to 584nm with a smooth surface, while SEM image of ZnO/Ag₂S composite shows the formation of Ag₂S layer over ZnO cores as indicated by rougher and contrasted surface as compared to bare ZnO cores. Also, the size of composite particles became larger than ZnO nanocores (100µm-200µm), which further confirms the formation of Ag₂S shell over ZnO nanocores. The optical absorption spectrums of both ZnO and ZnO/Ag₂S composite clearly indicate that synthesized composite absorb strongly in UV to IR region of the electromagnetic spectrum as compared to ZnO nanocores; which absorb only in UV region. Therefore, the synthesized composite could be used as a photovoltaic material.